Human T cell leukemia viruses (HTLV) comprise a family of exogenous human retroviruses. HTLV subtypes are characterized by differences in immunocompetition reactions of viral core proteins, and in nucleic acid hybridization heteroduplex maps, restriction enzyme analysis and DNA sequence analysis. HTLV-I is the etiologic agent of clinically aggressive adult T cell leukemia/lymphoma (ATLL), a disease characterized by an aggressive clinical course with a poor prognosis. By contrast, HTLV-II is an infrequent HTLV isolate orginally derived from a patient with a clinically benign T cell variant of hairy cell leukemia. Recently, a new group of HTLV viruses, HTLV III, have been isolated from patients with the acquired immune deficiency syndrome (AIDS). Although both HTLV-I and HTLV-II are associated with malignancies involving the mature OKT4+ subset of T lymphocytes, the clinical course and outcome of these malignancies differ markedly.
The full spectrum of diseases associated with HTLV is not known, and prior to this invention, the conventional widom has held that the factors which govern whether an HTLV will cause neoplasia, an immunodifficiency, or both, have not been defined. (Mitsuya, 1984).
The present invention describes a specific region of the HTLV genomes which governs the promotional strength, and host cell range for each virus. Also discussed is novel genomic factor, luk, which controls the tissue specificity for the various HTLV.